US11913236B2 - Mechanical locking system for floor panels - Google Patents

Abstract

Floor panels are shown, which are provided with a mechanical locking system that may be locked with a vertical displacement of a first panel against a second panel. The locking system includes a flexible strip that during locking bends upwardly or downwardly. The locking system includes a first and a second joint edge section with different locking functions. One section provides a horizontal locking and another section provides a vertical locking.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No. 16/745,613, filed on Jan. 17, 2020, which is a continuation of U.S. application Ser. No. 16/204,185, filed on Nov. 29, 2018, now U.S. Pat. No. 10,570,625, which is a continuation of U.S. application Ser. No. 15/726,754, filed on Oct. 6, 2017, now U.S. Pat. No. 10,161,139, which is a divisional of U.S. application Ser. No. 14/973,179, filed on Dec. 17, 2015, now U.S. Pat. No. 9,803,374, which claims the benefit of Swedish Application No. 1451632-2, filed on Dec. 22, 2014. The entire contents of U.S. application Ser. No. 16/745,613, U.S. application Ser. No. 16/204,185, U.S. application Ser. No. 15/726,754, U.S. application Ser. No. 14/973,179 and Swedish Application No. 1451632-2 are hereby incorporated herein by reference in their entirety.

TECHNICAL FIELD

The disclosure generally relates to the field of mechanical locking systems for floor panels and building panels. The disclosure includes panels, floorboards, locking systems and production methods.

FIELD OF APPLICATION

Embodiments of the present disclosure are particularly suitable for use in floating floors, which are formed of floor panels having one or more upper layers comprising, e.g., thermoplastic or thermosetting material or wood veneer, an intermediate core of wood-fibre-based material or plastic material and preferably a lower balancing layer on the rear side of the core. Embodiments of the disclosure may also be used for joining building panels which preferably contain a board material for instance wall panels, ceilings, furniture components and similar.

The following description of prior-art technique, problems of known systems and objects and features of the disclosure will therefore, as a non-restrictive example, be aimed above all at this field of application and in particular at laminate floors comprising an HDF core and formed as rectangular floor panels with long and shorts edges intended to be mechanically joined to each other on both long and short edges.

The long and short edges are mainly used to simplify the description of the disclosure. The panels may be square. Floor panels are generally produced with the surface layer pointing downwards in order to eliminate thickness tolerances of the core material. Some embodiments and production methods are shown with the surface pointing upwards in order to simplify the description.

It should be emphasized that embodiments of the disclosure may be used in any floor panel on long and/or short edges and it may be combined with all types of known locking systems on long or short edges that lock the panels in the horizontal and/or vertical direction.

BACKGROUND

Relevant parts of this background description are also a part of embodiments of the disclosed invention.

Several floor panels on the market are installed in a floating manner with mechanical locking systems formed at the long and short edges. These systems comprise locking means, which lock the panels horizontally and vertically. The mechanical locking systems are usually formed by machining of the core of the panel. Alternatively, parts of the locking system may be formed of a separate material, for instance aluminum or plastic material, which is integrated with the floor panel, i.e. joined with the floor panel in connection with the manufacture thereof.

Laminate flooring usually comprise a 6-8 mm wood based core, a 0.2 mm thick upper decorative surface layer of laminate and a 0.1 mm thick lower balancing layer. The laminate surface and the balancing layer comprise melamine-impregnated paper. The most common core material is fibreboard with high density and good stability usually called HDF—High Density Fibreboard. The impregnated surface and balancing papers are laminated to the core with heat and pressure. HDF material is hard and has a low flexibility, especially in the vertical direction perpendicular to the fibre orientation.

Recently a new type of powder based laminate floors has been introduced. Impregnated paper is replaced with a dry powder mix comprising wood fibres, melamine particles, aluminum oxide and pigments. The powder is applied on an HDF core and cured under heat and pressure. Generally high quality HDF is used with a high resin content and low water swelling. Advanced decors may be formed with digital printing. Water based ink is injected into the powder prior to pressing.

Luxury vinyl tile, LVT, flooring with a thickness of 3-6 mm usually comprises a transparent wear layer which may be coated with an ultraviolet, UV, cured polyurethane, PU, lacquer and a decorative plastic foil under the transparent foil. The wear layer and the decorative foil are laminated to one or several core layers comprising a mix of thermoplastic material and mineral fillers. The plastic core may be rather soft and flexible but also rather rigid depending on the filler content.

Wood Plastic Composite floors, generally referred to as WPC floors, are similar to LVT floors. The core comprises thermosetting material mixed with wood fibre fillers and is generally stronger and much more rigid than the mineral based LVT core.

Thermoplastic material such as PVC, PP or PE may be combined with a mix of wood fibres and mineral particles and this may provide a wide variety of floor panels with different densities and flexibilities.

Moisture resistant HDF with a high resin content, and WPC floors, comprise stronger and more flexible core materials than conventional HDF based laminate floors and they are generally produced with a lower thickness.

The above mentioned floor types comprise different core materials with different flexibility, density and strengths. Locking systems formed in one piece with the core must be adapted to such different material properties in order to provide a strong and cost efficient locking function.

Definition of Some Terms

In the following text, the visible surface of the installed floor panel is called “front side” or “floor surface”, while the opposite side of the floor panel, facing the sub floor, is called “rear side”. The edge between the front and rear side is called “joint edge”. By “horizontal plane” is meant a plane, which extends parallel to the front side. Immediately juxtaposed upper parts of two adjacent joint edges of two joined floor panels together define a “vertical plane” perpendicular to the horizontal plane. By “vertical locking” is meant locking parallel to the vertical plane. By “horizontal locking” is meant locking parallel to the horizontal plane.

By “up” is meant towards the front side, by “down” towards the rear side, by “inwardly” mainly horizontally towards an inner and center part of the panel and by “outwardly” mainly horizontally away from the center part of the panel.

By “essentially vertical” surface or wall is meant a surface or a wall that is inclined less than 45 degrees with respect to a vertical plane.

By “essentially horizontal” surface is meant a surface that is inclined less than 45 degrees with respect to a horizontal plane.

By locking angle of a surface locking panels in the horizontal direction is meant the angle of the surface relative to a vertical plane.

By locking angle of a surface locking panels in the vertical direction is meant the angle of the surface relative a horizontal plane.

A tangent line defines the inclination of a curved wall or surface.

Related Art and Problems Thereof

For mechanical joining of long edges as well as short edges in the vertical direction and horizontal direction perpendicular to the edges several methods may be used. One of the most used methods is the angle-snap method. The long edges are installed by angling. Horizontal snapping locks the short edges. The vertical connection is generally a tongue and a groove and the horizontal connection is a strip with a locking element in one edge that cooperates with a locking groove in the adjacent edge. Locking by snapping is obtained with a flexible strip that during the initial stage of locking bends downwards and during the final stage of locking snaps upwards such that the locking element is inserted into the locking groove.

Similar locking systems may also be produced with a rigid strip and they are connected with an angling-angling method where both short and long edges are angled into a locked position.

Advanced so-called “fold down locking systems” with a separate and flexible tongue on a short edge, generally called “5G systems”, have been introduced where both the long and short edges are locked with an angling action. A floor panel of this type is presented in WO 2006/043893. It discloses a floor panel with a short edge locking system comprising a locking element cooperating with a locking groove, for horizontal locking, and a flexible bow shaped so called “banana tongue” cooperating with a tongue groove, for locking in a vertical direction. The flexible bow shaped tongue is inserted during production into a displacement groove formed at the edge. The tongue bends horizontally along the edge during connection and makes it possible to install the panels by vertical movement. Long edges are connected with angling and a vertical scissor movement caused by the same angling action connects short edges. The snapping resistance is low and only a low thumb pressure is needed to press the short edges together during the final stage of the angling. Such a locking is generally referred to as “vertical folding”.

Similar floor panels are further described in WO 2007/015669. This invention provides a fold down locking system with an improved flexible tongue so called “bristle tongue” comprising a straight outer tongue edge over substantially the whole length of the tongue. An inner part of the tongue comprises bendable protrusions extending horizontally along the tongue body.

The above known fold down “5G system” has been very successful and has captured a major market share of the premium world laminate and wood flooring markets. The locking is strong and reliable mainly due to the flexibility and pretension of the separate flexible tongue that allows a locking with large overlapping essentially horizontal locking surfaces.

The 5G system and similar system have been less successful in the low priced market segments. The major reason is that the cost of the separate tongues and investments in special inserting equipment that is needed to insert a flexible tongue into a displacement groove are regarded as rather high in relation to the rather low price of the floor panels.

Several attempts have been made to provide a fold down locking system based on a vertical snapping function that may be produced in one piece with the core in the same way as the one piece horizontal snap systems. All such attempts have failed especially when a floor panel comprises an HDF core. This is not a coincidence. The failure is based on major problems related to material properties and production methods. Several of the known locking systems are based on theoretical geometries and designs that have not been tested in industrial applications. One of the main reasons behind the failure is that bending of vertically protruding parts that are used for the vertical locking of edges is limited to about 50% of the floor thickness or to about 4 mm in an 8 mm thick laminate floor panel. As comparison it may be mentioned that a protruding strip for horizontal snapping may extend over a substantial distance from the upper edge and may protrude 8-10 mm beyond the upper edge. This may be used to facilitate a downward bending of the strip and the locking element. Other disadvantages compared to horizontal snapping are that HDF comprises a fibre orientation substantially parallel with the floor surface. The material properties are such that bending of horizontally protruding parts is easier to accomplish than bending of vertically protruding parts. Furthermore, lower parts of an HDF board comprise a higher density and a higher resin content than middle parts and such properties are also favorable for the horizontal snapping systems where the strip is formed in the lower part of the core.

Another circumstance that has supported market introduction of the horizontal snap systems is the fact that a hammer and a knocking block may be used to snap the short edges. Fold down systems are so called tool-less systems and the vertical locking must be accomplished with hand pressure only.

It would be a major advantage if a one-piece fold down locking system may be formed with a quality and locking function similar to the advanced 5G systems.

SUMMARY OF THE DISCLOSURE

An objective of embodiments of the present disclosure is to provide an improved and more cost efficient fold down locking system for vertical and horizontal locking of adjacent panels wherein the locking system is produced in one piece with the core.

A first specific objective is to provide a locking system wherein a horizontally extending flexible strip may be used to accomplish the vertical and horizontal locking.

A second specific objective is to provide a locking system with essentially horizontally extending locking surfaces for the vertical locking such that a strong locking force may be obtained in the vertical direction.

A third specific objective is to prevent separation forces between the edges during locking and to decrease the snapping resistance such that a tool-less installation may be obtained with low pressure against the short edges.

A fourth specific objective is to provide a cost efficient method to form locking elements in a double-end tenor comprising a lower chain and an upper belt that displace the panel in relation to several tool stations.

The above objects may be achieved by embodiments of the disclosure.

According to a first aspect of the disclosure a set of essentially identical floor panels are provided with a mechanical locking system comprising a strip extending horizontally from a lower part of a first edge and a downwardly open locking groove formed in an adjacent second edge. The strip comprises an upwardly protruding locking element that is configured to cooperate with the locking groove and locks the first and the second edge in a horizontal direction parallel to a main plane of the first and the second panel and in a vertical direction perpendicularly to the horizontal direction. The locking system is configured to be locked with a vertical displacement of the second edge against the first edge wherein the strip, preferably an outer portion of the strip, during an initial stage of the vertical displacement is configured to bend upwards towards the second panel and during a final stage of the vertical displacement is configured to bend downwards towards its initial unlocked position.

An upper portion of the locking element may be configured to be displaced during locking into a space provided between an outer groove wall of the locking groove and an inner surface of the locking element. The displacement may be caused by at least one of a bending, a compression and a twisting of the strip. Optionally, the upper portion of the locking element may during locking be further configured to be displaced out from the space.

Bending may comprise rotation and/or a displacement of at least portions of the strip.

According to one embodiment, the space between the outer groove wall and the inner surface is a cavity arranged in the inner surface of the locking element. According to another embodiment, the space is a cavity arranged in the outer groove wall of the locking groove. According to yet another embodiment, the space is partly a cavity arranged in the inner surface and partly a cavity arranged in the outer groove wall.

The strip may be configured to bend upwards towards a portion of a front side of the second panel. The portion may be an outer portion of the front side.

Optionally, the upward and/or downward bending of the strip may be combined with at least one of a twisting or a compression of the strip.

The strip may be configured to bend upwards from the unlocked position to an end position. Moreover, the strip may be configured to bend downwards from the end position and at least partly back to the unlocked position. In a non-limiting example, an outer, lower portion of the strip is displaced vertically upwards from the unlocked position to the end position by a first distance and then is displaced vertically downwards by a second distance, wherein the second distance is between 10% and 95% of the first distance, e.g. 40% or 50%. In another non-limiting example, the strip bends completely back to a position corresponding to the unlocked position so that the second distance is essentially the same as the first distance.

The first and second panels may comprise a pair of parallel short edges and a pair of parallel long edges, wherein the long edges are perpendicular to the short edges. The first and second edges may be short edges.

The main plane of the first and the second panel may be a horizontal plane that is essentially parallel with the front side and/or the rear side of the first and/or the second panel.

By a vertical displacement is meant that the edges of the panels are displaced against each other at least in a vertical direction. Optionally, however, the vertical displacement may also be combined with an angling action. According to one embodiment, the vertical displacement is a vertical scissor movement caused by the same angling action that is used to connect the edges of the panels that are perpendicular to the first and the second edges. For example, the first and second edges may be short edges and the perpendicular edges may be long edges. According to another embodiment, front sides of the first and second panels are essentially parallel to each other during the vertical displacement.

The first and the second edge may comprise a first edge section and a second edge section along the first and the second edge, wherein a cross section of the locking groove or a cross section of the locking element varies along the first edge and/or the second edge, in a locked position.

The cross section of the locking groove or of the locking element may be a cross section as seen from a side view of the floor panels.

There may be at least one first edge section and at least one second edge section. A shape of the each of the first edge sections may be similar. Moreover, a shape of each of the second edge sections may be similar. Alternatively, the shapes of the first edge sections and/or the second edge sections may vary.

The first edge sections and the second edge sections may be arranged alternately along the first and the second edge.

There may be a smooth transition between the first and the second edge sections along the edge. Alternatively, the transition between the first and the second edge sections along the edge may be stepped.

According to one embodiment, a first edge section is arranged at a first and/or a second corner section of the first and second edges. According to one embodiment, a second edge section is arranged at a first and/or a second corner section of the first and second edges.

In any of these embodiments, the first and second corner sections may be arranged adjacent to long edges of the panels.

According to one embodiment, the first and second edges are locked vertically by means of engagement of an upper locking surface provided on an outer surface of the locking element and a lower locking surface provided on an inner groove wall of the locking groove. In one example, the upper locking surface is provided along the entire first edge and the lower locking surface is provided along a part of the second edge. In another example, the upper locking surface is provided along a part of the first edge and the lower locking surface is provided along the entire second edge.

During the final stage the locking element may be snapped into the locked position such that the upper and lower locking surfaces engage with each other in the locking position. Alternatively, the locking element may assume the locked position by means of a smooth displacement upwards and/or downwards such that the upper and lower locking surfaces engage with each other in the locking position. For example, the latter may be achieved with a beveled upper and/or lower locking surface. The strip may also be pressed down by a lower part of the second panel that presses against an upper part of the protruding strip and/or the locking element.

According to a second aspect of the disclosure a set of essentially identical rectangular floor panels each comprising long edges and a first short edge and a second short edge are provided. The first short edge and the second short edge are provided with a mechanical locking system comprising a strip extending horizontally from a lower part of a first short edge and a downwardly open locking groove formed in the second short edge. The strip comprises an upwardly protruding locking element that is configured to cooperate with the locking groove for locking the first short edge and the second short edge in a horizontal direction parallel to the main plane of the panels and in a vertical direction perpendicularly to the horizontal direction. The locking element comprises an inner surface, an outer surface and a top surface. The inner surface is positioned closer to an upper edge of the first panel than the outer surface. The locking groove comprises an outer groove wall, an inner groove wall and an upper groove wall, the outer groove wall being positioned closer to an upper edge of the second panel than the inner groove wall. The locking element comprises an upper locking surface and the locking groove comprises a lower locking surface. In a locked position the first short edge and the second short edge comprise a first and a second joint edge section located along the first short edge and the second short edge. The first edge section is configured such that the outer groove wall of the locking groove and the inner surface of the locking element along are in contact with each other along a horizontal plane HP and lock the first short edge and the second short edge horizontally, and the second edge section is configured such that along the horizontal plane HP there is a space between the outer groove wall of the locking groove and the inner surface of the locking element. The upper locking surface of the locking element and the lower locking surface of the locking groove are configured to be in contact with each other and to lock the first short edge and the second short edge vertically.

Embodiments of the space between the outer groove wall and the inner surface are largely analogous to the embodiments described above in relation to the first aspect, wherein reference is made to the above. In addition, a length of the space in a length direction of the short edges may correspond to a length of the second edge section. Alternatively, the length of the space may be longer than the length of the second edge section.

The upper locking surface of the locking element and the lower locking surface of the locking groove may be configured to be in contact with each other in the second edge section.

The upper locking surface and the lower locking surface form an overlap in a direction parallel with the main plane of the panels and perpendicularly to the short edges. Preferably, there is an overlap only along a portion of the short edges, e.g. in the second edge section(s). In a first example, the overlap is constant along the short edges. More specifically, the overlap is constant in the second edge section(s). In a second example, the overlap varies along the short edges. The varying overlap may be periodic with a constant periodicity along the second edge section(s).

According to one embodiment, the upper locking surface extends along the entire first short edge. In a non-limiting example, there is no lower locking surface provided in the first edge section.

According to one embodiment, the lower locking surface extends along the entire second short edge. In a non-limiting example, there is no upper locking surface provided in the first edge section.

The upper locking surface or the lower locking surface may extend along a portion of the first and second short edge, respectively.

According to a non-limiting embodiment, the upper locking surface is arranged only in a middle section of the first short edge and the lower locking surface is provided along the entire second short edge. Thereby, the upper locking surface is missing from corner sections of the first short edge, wherein the middle section is a second edge section and the corner sections are first edge sections, the middle section being arranged between the corner sections. The overlap is thereby formed only in the middle section. According to this embodiment, the space is formed as a cavity in a middle portion of the outer groove wall and/or in a middle portion of the inner surface.

The upper edge of a panel may be a portion of the panel along a short edge thereof. The upper edge may be closer to the front side than the rear side of the panel. Moreover, the upper edge of the first panel may be provided in a side wall of an indentation provided along the first short edge of the first panel. A projection along the second short edge of the second panel may be adapted to be inserted in the indentation. Moreover, the upper edge of the second panel may be provided in the second short edge of the second panel.

The first edge section may be located closer to a long edge than the second edge section. Alternatively, the second edge section may be located closer to a long edge than the first edge section. The first and/or second edge sections may be arranged at corner sections in precise analogy to the first aspect explained above.

The locking system may be configured to be locked with a vertical displacement of the second short edge against the first short edge. The concept of “vertical displacement” has been defined above in relation to the first aspect.

The locking system may be configured such that a vertical displacement of the second short edge against the first short edge during an initial stage of the vertical displacement bends the strip upwards towards the second panel such that the upper locking surface and lower locking surface overlap each other.

The strip may be configured to bend upwards towards a portion of a front side of the second panel. The portion may be an outer portion of the front side. The upward bending of the strip may comprise at least one of an upward vertical displacement, a horizontal displacement inwards, and a rotation. Optionally, the upward bending may be combined with a twisting and/or a compression of the strip.

The lower locking surface may be essentially horizontal. Alternatively, the lower locking surface may be inclined. The angle of the lower locking surface with respect to a main plane of the second panel may be between 0° and 45° degrees, e.g. 15, 20° or 25°.

According to one embodiment, the lower locking surface is planar. According to an alternative embodiment, however, the lower locking surface may be curved. The curvature may be positive or negative, i.e. convex or concave, in a direction perpendicular to the vertical plane.

A shape of the lower locking surface may correspond to a shape of the upper locking surface—partly or entirely.

A tangent line TL to the lower locking surface may intersect the outer wall of the locking groove.

The upper locking surface may be located on the outer surface of the locking element. The lower locking surface may be located on the inner grove wall of the locking groove.

The upper locking surface may be spaced vertically upwards from an upper strip surface. The upper strip surface may be surface provided on the strip of the first short edge. The upper strip surface may be at least partially planar. Moreover, a portion of the upper strip surface may be curved. In a locked position, at least a portion of the upper strip surface may engage with a projection of the second short edge of the second panel. In particular, at least a portion of the upper strip surface may engage with the projection in a first edge section as well as in a second edge section.

According to a third aspect of the disclosure a set of essentially identical floor panels are provided with a mechanical locking system comprising a strip extending horizontally from a lower part of a first edge and a downwardly open locking groove formed in an adjacent second edge. The strip comprising an upwardly protruding locking element which is configured to cooperate with the locking groove for locking the first edge and the second edge in a horizontal direction parallel to a main plane of the panels and in a vertical direction perpendicularly to the horizontal direction. The locking element and the locking groove comprise an upper and a lower locking surface, which are configured to lock the panels vertically. The floor panels are characterized in that the upper locking surface is located on an upper part of the locking element facing an upper edge of the first panel, and that the upper locking surface is inclined or rounded and extends from the locking element and towards an inner part of the panel such that a tangent line to the upper locking surface of the locking element intersects the edge.

The upper part of the locking element may face the upper edge of the first panel. Moreover, the tangent line may intersect the first edge.

The tangent line may be specified in a cross-sectional side view of the panels. The tangent line may intersect the first edge at an upper part of the first edge.

In one non-limiting example, the upper locking surface is planar. In this case, the planar upper locking surface may be inclined with respect to a front side of the first panel by an angle between 0° and 45°, e.g. 20° or 25°. In another non-limiting example, the upper locking surface is rounded or, equivalently, curved. In this case, the curvature of the upper locking surface may be positive or negative, or put differently: the upper locking surface may be convex or concave in a direction perpendicular to the vertical plane. In case of a rounded upper locking surface, tangent lines at one or several points of the upper locking surface may intersect the first edge, as seen from a cross-sectional side view of the panels.

A shape of the upper locking surface may correspond to a shape of the lower locking surface—partly or entirely.

The locking system may be configured to be locked with a vertical displacement of the second edge against the first edge.

The locking system may be configured such that a vertical displacement of the second edge against the first edge during locking bends the strip downwards and turns the upper part of the locking element outwardly away from the upper edge.

The locking surfaces may be configured such that the upper and lower locking surfaces comprise upper and lower guiding surfaces that overlap each other during the downward bending of the strip.

According to a fourth aspect of the disclosure, there is provided a method for producing a locking system at edges of building panels. The building panels comprise a core and a locking surface formed in the core and extending essentially horizontally such that a tangent line to a part of the locking surface intersects an essentially vertical adjacent wall formed in the panel edge adjacent to the locking surface. The method comprises:

• • forming a strip at a lower part of a first edge of a panel and a locking element at an outer part of the protruding strip,
  • forming a locking groove in a second edge of the panel, and
  • forming the essentially horizontal locking surface in a wall of the locking groove or on the locking element by displacing the panel against a fixed carving tool.

According to a fifth aspect of the disclosure, a set of essentially identical floor panels are provided with a mechanical locking system comprising a strip extending horizontally from a lower part of a first edge and a downwardly open locking groove formed in an adjacent second edge. The strip comprises an upwardly protruding locking element that is configured to cooperate with the locking groove and locks the first and the second edge in a horizontal direction parallel to a main plane of the first and the second panel and in a vertical direction perpendicularly to the horizontal direction. The locking system is configured to be locked with a vertical displacement of the second edge against the first edge, wherein an upper portion of the strip is configured to bend upwards towards the second panel.

Optionally, the upward bending of the strip may be combined with at least one of a twisting or a compression of the strip and/or the locking element.

The fifth aspect of the disclosure is largely analogous to the first aspect, except for the final stage of the vertical displacement downwards, wherein reference is made to the above embodiments and examples discussed in relation therewith.

Additionally, the locking element may assume the locked position by means of a smooth displacement upwards such that upper and lower locking surfaces may engage with each other in the locking position. Alternatively, it may snap into the locked position.

According to a sixth aspect of the disclosure, a set of essentially identical floor panels are provided with a mechanical locking system comprising a strip extending horizontally from a lower part of a first edge and a downwardly open locking groove formed in an adjacent second edge. The strip comprises an upwardly protruding locking element that is configured to cooperate with the locking groove and locks the first and the second edge in a horizontal direction parallel to a main plane of the first and the second panel and in a vertical direction perpendicularly to the horizontal direction. The locking system is configured to be locked with a vertical displacement of the second edge against the first edge, wherein a portion of the strip is configured to be displaced in a direction inwards by twisting and/or compressing the strip.

The sixth aspect of the disclosure is largely analogous to the first aspect, except that the upward and downward bending have been replaced by twisting and/or compression of the strip, wherein reference is made to the above embodiments and examples discussed in relation therewith. In particular, the portion of the strip may be a portion of the locking element, e.g. an upper portion of the locking element. Moreover, the upper portion of the locking element may be configured to be displaced during locking into a space provided between an outer groove wall of the locking groove and an inner surface of the locking element.

Additionally, the locking system may be further configured to be locked with a displacement of the portion of the strip in a direction outwards. For example, the strip may be untwisted and/or decompressed at least partly towards an initial unlocked position of the strip.

According to a seventh aspect of the disclosure, there is provided a set of essentially identical floor panels comprising a first panel and an adjacent second panel and being provided with a mechanical locking system comprising a strip extending horizontally from a lower part of a first edge of the first panel and a first downwardly open locking groove and a second downwardly open locking groove formed in a second edge of the second panel. The strip comprises a first upwardly protruding locking element and a second upwardly protruding locking element provided inwardly of the first locking element. Moreover, the second locking element is configured to cooperate with the second locking groove and to lock the first and the second edges in a horizontal direction perpendicular to a vertical plane defined by the joint adjacent first and second edges. The first locking element is configured to cooperate with the first locking groove and to lock the first and second edges in a vertical direction perpendicularly to said horizontal direction. The locking system is configured to be locked with a vertical displacement of the second edge against the first edge whereby an upper portion of the locking element is displaced into a space. The space is defined by a cavity between an outer groove wall of the first locking groove and an inner surface of the first locking element in a locked state of the panels.

According to one embodiment, the first and the second locking grooves are separated by a downwardly extending projection.

According to another embodiment, the first and the second locking groove are part of a common groove. The common groove may have an inner wall coinciding with a wall of the first locking groove and an outer wall coinciding with a wall of the second locking groove. Moreover, the common groove may have an intermediate wall connecting upper groove walls of the first and the second locking groove.

The seventh aspect of the disclosure is largely analogous to the first aspect, wherein reference is made to the above embodiments and examples discussed in relation therewith. In particular, it is understood that the upper portion of the locking element may optionally bend upwards, may be compressed and/or twisted, and may possibly also be bended downwards. Also, all the embodiments of the space according to the first aspect may be combined with the seventh aspect.

More generally, it is emphasized that the embodiments according to the various aspects of the disclosure may be combined in part or in their entirety with each other. Additionally, it is understood that in all of the above aspects the bending, twisting, compression, or deformation may be elastic or inelastic.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will in the following be described in connection to exemplary embodiments and in greater detail with reference to the appended exemplary drawings, wherein:

FIGS.1a-1gillustrate a fold down locking systems according to known principles.

FIGS.2a-2cillustrate known principles to form locking systems.

FIGS.3a-3eillustrate vertical folding and edge separation.

FIGS.4a-4fillustrate bending of protruding parts.

FIGS.5a-5billustrate a first and a second edge section of a locking system according to one embodiment.

FIGS.6a-6billustrate the first and second edge sections of the locking system inFIGS.5a-5bin a locked position.

FIGS.7a-7dillustrate alternative embodiments of the first and second edge sections.

FIGS.8a-8cillustrate a vertical displacement of a first edge section according to an embodiment.

FIGS.9a-9eillustrate a vertical displacement of a second edge section according to an embodiment.

FIGS.10a-10cillustrate jumping tool heads and rotating carving tools according to an embodiment.

FIGS.11a-11fillustrate forming of an edge section with jumping tool heads according to an embodiment.

FIGS.12a-12billustrate forming with carving tools according to different embodiments.

FIGS.13a-13eillustrate a panel edge comprising a first and a second edge section according to an embodiment.

FIGS.14a-14eillustrate different embodiments of locking systems and their formation.

FIGS.15a-15dillustrate a locking system according to a second principle.

FIGS.16a-16cillustrate a locking system edge section according to the second principle.

FIGS.17a-17dillustrate a method to strengthen a protruding part according to an embodiment.

FIGS.18a-18fillustrate an embodiment of a production method to form a locking system.

FIGS.19a-19fillustrate another embodiment of a production method to form a locking system.

FIGS.20a-20dillustrate locking of long and short edges according to an embodiment and forming of a locking system according to an embodiment.

FIGS.21a-21eillustrate a long edge locking system according to an embodiment.

FIGS.22a-22dillustrate a long edge locking system according to an embodiment.

FIGS.23a-23dillustrate locking of furniture components according to an embodiment.

FIGS.24a-24fillustrate a locking system formed according to a third principle.

FIGS.25a-25dillustrate various embodiments of flex grooves provided in the second floor panel.

FIGS.26a-26billustrate various embodiments of slits provided in the first floor panel.

FIGS.27a-27cillustrate an embodiment with a flexible and a bendable locking element.

DETAILED DESCRIPTION

FIGS.1a-1fshow some examples of known fold down locking systems made in one piece with thecore5 that are intended to lock short edges with a vertical displacement of a second edge of asecond panel1′ against a first edge of afirst panel1. All systems comprise a horizontally protrudingstrip6 with alocking element8 in the first edge of thefirst panel1 that cooperates with a lockinggroove14 in the second edge of thesecond panel1′ and locks the edges of thepanels1,1′ horizontally. Different methods are used to lock the edges vertically.

FIG.1ashows that asmall tongue10 that cooperates with a tongue groove9 may be used for the vertical locking. Compression of thetongue10 is required to accomplish the locking. The upper edges are, during the vertical displacement, spaced from each other with a space S that corresponds to the horizontal protrusion of thetongue10. The adjacent edges must be pulled together during the final stage of the locking. The friction between the long edges, that during the final stage of the locking are practically aligned horizontally and are in a locked position, prevents such pulling together and there is a major risk that the edges are locked with a space or that the lockingelement8 is damaged. A considerable pressure force is required to press the edges together and thickness tolerances may create further problems, especially if thesecond panel1′ is thicker than thefirst panel1 and will hit the subfloor before the upper surfaces are aligned horizontally. The locking system is not suitable to lock panels comprising, for example, an HDF core or other non-compressible materials.

FIG.1bshows a similar locking system with twotongues10a,10band two tongue grooves9a,9b. This system requires material compression and creates edge separation during locking. The locking surfaces are almost vertical and have a locking angle LA of about 60 degrees with respect to a horizontal plane H. The protruding tongues are very small and protrude a few tenths of a millimeter and this corresponds to normal production tolerances resulting in locking system that are not possible to lock or without any overlapping locking surfaces.

FIG.1cshows a locking system with twotongues10a,10b. The locking element comprises a locking surface that is inclined upwardly towards the upper edge in order to increase the vertical locking strength. This locking system is even more difficult to lock than the locking systems described above and suffers from the same disadvantages.

FIG.1dshows an embodiment that is based on downwardly protruding locking elements that are intended to bend inwardly against each other such that twotongues10a,10bmay be inserted into tongue grooves. The flexibility that may be obtained over the limited vertical extension of the locking elements in an HDF material is not sufficient to obtain a locking force necessary for flooring applications. However, the locking system eliminates separation forces during locking.

FIG.1eshows a locking system wherein similar flexibility is obtained with a groove formed behind the lockinggroove14. Such locking systems suffer from the same disadvantages as the locking system shown inFIG.1d. Similar locking system may also comprise lockingsurfaces10b,9bthat are shortened in regions, for example as described in WO 2010/100046, in order to reduce damages of the locking means during installation when material is compressed. In practice no reduction of damages may be obtained.

FIG.1fshows a locking system comprising astrip6 that is bended downwards during the vertical displacement. The locking system is intended to be used together with an installation method wherein the long edges of the first and the second panels are in an angled position such that the friction forces are reduced to a level where the locking element during upward snapping is capable to automatically pull the edges together. The major disadvantage is that the installation must be made with panels in angled position and this is more complicated than the conventional single action fold down installation.

FIG.1gshows locking systems that may compriseslits6ain the locking strip, for example as described in US 2010/0037550 or slits14abehind the locking groove, for example as described in WO 2008/116623. Such slits may increase the flexibility and the horizontal displacement possibilities of the locking elements considerably and a very easy locking may be obtained. The main problem is that such slits also increase the vertical flexibility and flexibility. This will result in a very low locking strength in the vertical direction. Therefore attempts to introduce such locking systems have failed.

FIGS.2a-2cshow that the geometry of the locking systems is restricted in several ways by the production methods wherein double-end tenors comprising achain33, abelt34 and several largerotating tools17 with a diameter of about 20 cm are used.FIGS.2aand2bshow that efficient production methods require that grooves and protrusions are formed withrotating tools17 that rotate vertically or horizontally or that are angled away from thechain33 and thebelt34.FIG.2cshows that only essentially vertical locking surfaces may be formed on an inner part of thelocking element8 or on the lockinggroove14 and that very small rotating tools with a low milling capacity may be used. Several of the known locking systems are not possible to produce in a cost efficient way.

FIGS.3a-3eexplain the separation forces that may occur during vertical folding when asecond panel1′ is angled against a previously installedpanel1″ in a previous row and wherein this angling action also connects a short edge of thesecond panel1′ to a short edge of afirst panel1 as shown inFIG.3a. The short edges are locked with a scissor like movement wherein the short edges are gradually locked from one long edge to the other long edge. The adjacent short edges of the first and thesecond panels1,1′ have along their edges astart section30 that becomes active during a first initial step of the folding action, amiddle section31 that becomes active during a second stage of the folding action and anend section32 that becomes active during a final third step of the folding action. The shown locking system is based on an embodiment with astrip6 that during vertical displacement bends downwards and thereafter snaps upwards.FIG.3bshows that one part of the edge, that is close to the long edge where the angling takes place, is almost in locked position, as shown by the cross section A-A, when the lockingelement8 and the lockinggroove14 of middle sections B-B are still spaced from each other vertically, as shown inFIG.3c, and when edge sections C-C that are most distant to the long edge where angling takes place are spaced from each other vertically without any contact between the cross sections C-C as shown inFIG.3d.FIG.3eshows the final step of the locking when the edges must be pulled together with a pulling force that is sufficient to overcome the friction between long edges of the firstinstalled panel1″ and thesecond panel1′. The friction may be substantial, especially when the panels are long or when a high friction material is used as a core. The high friction is to a large extent caused by the geometry of the long edge locking system that must be formed with a tight fit between the tongue and the tongue groove in order to avoid squeaking sound.

FIGS.4aand4bshow a one piece locking system formed in a laminate floor panel comprising an HDF core. The locking system is locked with horizontal snapping. The HDF material compriseswood fibres24 that during HDF production obtain an essentially horizontal position in the core material. The density profile is such that the upper5aand the lower5bparts of thecore5 have a higher density than the middle parts. These outer portions are also reinforced by the melamine resin from the impregnated paper of thesurface2 and in the balancing layers3 that during lamination penetrates into thecore5. This allows that a strong andflexible strip6 may be formed that, during locking, bends downwards. The snapping function is supported by the upper lip9′ that bends slightly upwards and the protrudingtongue10 that bends slightly downwards. The locking element may easily be formed with a high locking angle and with essentially vertical locking surfaces.

As a comparison, bending of vertically protrudinglocking elements8 are shown inFIGS.4c-4f.FIGS.4cand4dshow alocking element8 that during vertical displacement is bended outwardly. The bending takes place in the rather soft part of the HDF core and acrack23 will generally occur in the lower part of thelocking element8.FIGS.4eand4fshow alocking element8 that is used to lock against a lockinggroove14 in a horizontal H and a vertical direction V. The locking can only take place with material compression and this causes damages and cracks23,23′ in the locking system.

FIGS.5aand5bshow a first embodiment of the disclosure according to a first main principle. A set ofsimilar floor panels1,1′ are provided, wherein each floor panel preferably comprises asurface layer2, acore5, abalancing layer3 and a first and a second short edge. A firstshort edge4cof afirst floor panel1 may be locked to an adjacent secondshort edge4dof a similarsecond floor panel1′ with a vertical displacement of the second edge against the first edge. According to the present embodiment, the vertical displacement is a vertical scissor movement caused by the same angling action that is used to connect the long edges of the panels. The firstshort edge4ccomprises a horizontally protrudingstrip6 with a vertically protruding lockingelement8 at its outer part that cooperates with a downwardlyopen locking groove14 formed in the adjacentsecond edge4d.

According to the present embodiment, the lockingelement8 is essentially rigid and is not intended to be bended or compressed during locking that contrary to known technology is accomplished essentially with a horizontal displacement of the upper part of thelocking element8 towards the upperfirst edge43. By essentially rigid is here meant that during locking the locking element itself is bended and/or compressed in a horizontal direction by a distance HD that is less than 50% of a horizontally protruding upper locking surface11alocated in the upper part of thelocking element8 as shown inFIG.6b. The displacement of thelocking element8 is mainly accomplished with a bending and/or deformation of thestrip6. The locking element comprises aninner surface8a, anouter surface8band an upper ortop surface8c. Theinner surface8ais closer to anupper edge43 of thefirst panel1 than theouter surface8b. More specifically, a horizontal distance between theinner surface8aand theupper edge43 is smaller than a horizontal distance between theouter surface8band theupper edge43. According to the present embodiment, theupper edge43 is a portion of the first edge close to the front side of thefirst panel1. Moreover, theupper edge43 is provided in aside wall45 of anindentation44 which is provided in the first edge. Theindentation44 is upwardly open and, in a locked position, anupper support surface16 of aprojection46 provided in the second edge engages with alower support surface15 of the indentation which is a portion of anupper strip surface6aof thestrip6. The lockinggroove14 comprises an outer groove wall14a, aninner groove wall14band anupper groove wall14c. Theprojection46 is provided outside of the lockinggroove14 and share the outer groove wall14awith the lockinggroove14. The outer groove wall14ais closer to anupper edge43′ of thesecond panel1′ than theinner groove wall14b. More specifically, a horizontal distance between the outer groove wall14aand theupper edge43′ is smaller than a horizontal distance between theinner groove wall14band theupper edge43′. The lockingelement8 comprises an upper locking surface11aformed in theouter surface8bof thelocking element8 that cooperates with alower locking surface11bformed in theinner groove wall14band that locks the adjacent edges in a vertical direction. The upper11aand the lower11blocking surfaces are spaced vertically upwards from theupper surface6aof thestrip6. For example, the upper11aand the lower11blocking surfaces may be spaced vertically upwards with a vertical locking distance VLD from the entireupper surface6aor from an uppermost part of theupper surface6a, e.g. thelower support surface15 of theindentation40. In non-limiting examples, VLD may be between 20% and 70%, e.g. 30%, 40% or 50%, of a thickness T of the floor panels in the vertical direction. The lockingelement8 comprises afirst locking surface12aformed in theinner surface8aof thelocking element8 that cooperates with asecond locking surface12bformed in the outer groove wall14aand that locks the adjacent edges in a horizontal direction.

According to an alternative embodiment, the lockingelement8 may be configured to bend during locking.

Adjacent edges comprise in locked position afirst edge section7aand asecond edge section7b. The edge sections are characterized in that a cross section of the lockinggroove14 and/or a cross section of thelocking element8 varies along the adjacent edges of thepanels1,1′ which are formed with a basic geometry that is thereafter modified such that the first7aand the second7bcooperating edge sections are formed with different geometries and different locking functions. Here, the geometries and cross sections are specified in a side view of the panels as shown inFIGS.5aand5b.

Thefirst edge section7ais preferably astart section30 that becomes active during a first initial step of the folding action and thesecond edge section7bis preferably asubsequent section31 or amiddle section31 that becomes active during a second step of the folding action.

It is clear that, according to an alternative embodiment, thesecond edge section7bmay be astart section30 that becomes active during a first initial step of the folding action and that thefirst edge section7amay be asubsequent section31 or amiddle section31 that becomes active during a second step of the folding action. This is shown inFIG.26b.

FIG.5ashows a first cooperatingedge section7athat is used to prevent edge separation during locking and to lock adjacent edges horizontally in the locked position. Thefirst edge section7ahas no vertical locking function since one of the locking surfaces, in this preferred embodiment the upper locking surface11a, has been removed. The first12aand the second12blocking surfaces are preferably vertical and they are used to guide thesecond panel1′ during the vertical displacement along a vertical plane VP that intersects the upper and outer edge21 of thefirst panel1.

The first12aand the second12blocking surfaces may be inclined with respect to the vertical plane VP. Such geometry may be used to facilitate unlocking of the short edges with an angling action. A locking system with vertical first12aand second12blocking surfaces may be unlocked with a sliding action along the short edges.

FIG.5bshows thesecond edge section7bthat is used to lock the adjacent edges vertically. Thesecond edge section7bcannot prevent edge separation and has no horizontal locking function since a part of thelocking element8 and/or the lockinggroove14 has been removed in order to form a space S along a horizontal plane HP that allows a turning or displacement of thelocking element8 inwardly during locking when thesecond edge1′ is displaced vertically along the vertical plane VP. The turning of thelocking element8 is mainly caused by an upward bending of a part of thestrip6 within thesecond edge section7bthat takes place when a horizontal pressure is applied by a part of theinner groove wall14bon theouter surface8bof thelocking element8 during the vertical displacement of thesecond edge4dagainst thefirst edge4c. Such locking function provides major advantages. No material compression is required and the material properties of the protruding strip may be used to obtain the necessary flexibility that is needed to displace the upper part of thelocking element8 in order to bring the upper and lower locking surfaces11a,11bin a locked position.

According to the present embodiment, the space S has a vertical extension substantially corresponding to a vertical extension of theinner surface8aso that it extends down to theupper strip surface6a. It is clear that, according to alternative embodiments (not shown), the space S may have a smaller vertical extension. Preferably, however, the space S is located at an upper part of thelocking element8. Moreover, the vertical extension is preferably larger than a vertical extension of an upper protrudingpart25 formed on an outer and upper part of thelocking element8, e.g. 1.5, 2 or 3 times larger.

In a first example, the vertical extension of the space S varies along the edge. The vertical extension may vary along the edge from a minimal vertical extension to a maximal vertical extension and then, optionally, back to a minimal vertical extension. The variation may be smooth.

In a second example, the vertical extension of the space S is constant along the edge. A first and a second wall of the space S that are spaced from each other along the edge may be vertical and parallel.

By way of example, the space S may be formed by means of milling, scraping, punching, perforation or cutting.

Thestrip6 and thelocking element8 are during locking twisted along the first short edge. In thefirst edge section7a, thestrip6 is essentially in a flat horizontal position during locking and in thesecond edge section7bthestrip6 is bended upwards and thelocking element8 with its upper locking surface is turned and/or displaced inwardly during locking.

Optionally, or alternatively, at least portions of thestrip6 may be twisted and/or compressed during locking. For example, a portion between a lower part of thestrip6band theupper strip surface6aand/or thelocking element8 of thestrip6 may be twisted and/or compressed. The twisting may occur at least around an axis that is perpendicular to the vertical plane VP. The compression may occur at least inwardly in a horizontal direction that is perpendicular to the vertical plane VP. In particular, thestrip6 may be twisted in the transition regions between the first7aand second7bedge sections. Moreover, thestrip6 may become compressed in thesecond edge section7band such compression may facilitate a displacement of thelocking element8 even in rather rigid materials since the material content of thestrip6 is much larger than the material content of thelocking element8. As an example it may be mentioned that the lockingelement8 may have a horizontal extension of about 4 mm and thestrip6 may protrude horizontally about 8 mm from theside wall45 and to theinner surface8aof the locking element. At a compression of 1%, the locking element will contribute with 0.04 mm or with about ⅓ of a total compression and the strip with 0.08 mm or with about ⅔ of the total compression. Generally, the locking element in an HDF based laminate floor must be displaced horizontally with a distance of at least 0.2 mm in order to provide sufficient locking strength. 0.4 mm is even more preferred. Depending on the joint geometry and material properties about ⅓ of the necessary displacement may be accomplished with material compression and ⅔ with bending and turning or twisting of the strip and the locking element.

The upper11aand lower11blocking surfaces are preferably essentially horizontal. The locking surfaces are in the showed embodiment inclined with respect to a horizontal plane HP with a locking angle LA that is about 20 degrees. The locking angle LA is preferably 0-45 degrees. Locking surfaces with low locking angles are preferred since they provide a stronger vertical locking. The most preferred locking angle LA is about 5-25 degrees. However it is possible to reach sufficient locking strength in some applications with locking angles between 45 and 60 degrees. Even higher locking angles may be used but such geometries will decrease the locking strengths considerably.

FIGS.6aand6bshow the first7aand the second7bedge sections in a locked position. Thefirst edge section7ais configured such that the outer groove wall14aof the lockinggroove14 and theinner surface8aof thelocking element8 are in contact with each other along a horizontal plane HP and lock the first short edge and the second short edge horizontally and thesecond edge section7bis configured such that along the same horizontal plane HP there is a space S between the outer groove wall14aof the lockinggroove14 and theinner surface8aof thelocking element8. The space S allows that the lockingelement8 may be turned and/or displaced inwardly. Thefirst edge section7ais also preferably configured such that there is no vertical locking and no turning and/or displacement of thelocking element8 since at least one of the locking surfaces11a,11bhas been removed and thesecond edge section7bis configured such that it comprises upper11aand lower11blocking surfaces that lock the edges vertically and upper25 and lower26 protruding parts that during locking press, displace and/or turn thelocking element8 inwardly. Also compression and/or twisting are possible.

FIG.6ashows thefirst edge section7ain a locked position. Thefirst locking surface12aformed on theinner surface8aof thelocking element8 is in contact with thesecond locking surface12bformed on the inner groove wall14aof the lockinggroove14. The first12aand the second12blocking surfaces lock the adjacent edges horizontally and prevent a horizontal separation of thepanels1,1′.

FIG.6bshows thesecond edge section7bin a locked position. The upper locking surface11aformed on theouter surface8bof thelocking element8 is in contact with thelower locking surface11bformed on theinner groove wall14bof the lockinggroove14. The upper11aand lower11blocking surfaces lock the adjacent edges vertically and prevent a vertical separation of thepanels1,1′.

According to the present embodiment, there is anintermediate cavity47 provided between a portion of theupper support surface16 and a portion of theupper strip surface6a. Since a thickness of thestrip6 in this area is smaller than at the location of thelower support surface15, the strip may be bended more easily. Theupper support surface16 preferably is a planar surface and theprojection50 preferably has a constant thickness in a direction perpendicular to the vertical plane VP as measured from itssurface layer2. The thickness is preferably also constant along the edge of thesecond panel1′.

According to an alternative embodiment (not shown), however, the thickness of theprojection50 may vary in a direction perpendicular to the vertical plane VP. Thereby, least a portion of theprojection46 may extend below thelower support surface15.

The space S is an essential feature in this embodiment of the disclosure. A horizontal extension of the space S along a horizontal plane HP that intersects the upper11aand lower11blocking surfaces preferably exceeds a horizontal distance HD of the upper and lower locking surfaces. Here, the horizontal extension of the space S may be a maximal horizontal extension.

FIG.7ashows a preferred embodiment of thefirst edge section7awhere a part of theinner groove wall14band thelower locking surface11bhave been removed.FIG.7bshows a preferred embodiment of thesecond edge section7bwhere a part of the outer groove wall14ahas been removed in order to form the space S that allows the lockingelement8 to turn inwardly during locking.

According to the present embodiment, the space S has a vertical extension substantially corresponding to a vertical extension of the outer groove wall14aso that it extends up to theupper groove wall14c. It is clear that, according to alternative embodiments (not shown), the space S may have a smaller vertical extension. Preferably, however, the space S is located adjacent to theupper groove wall14c. Moreover, the vertical extension is preferably larger than a vertical extension of the upper protrudingpart25, e.g. 1.5, 2 or 3 times larger.

The vertical extension of the space S may vary or may be constant along the edge as explained above in relation to the embodiment inFIGS.5a-b.

FIGS.7cand7dshow that the embodiments shown inFIGS.5a,5band7a,7bmay be combined. As shown inFIG.7c, thefirst edge section7aconfigured to prevent edge separation and to lock horizontally may be formed according toFIG.7aand thesecond edge section7bcomprising the space S and configured to bend and to lock vertically may be formed according toFIGS.5band6b. Alternatively, as shown inFIG.7d, thefirst edge7asection may be formed according toFIG.5aor6aand thesecond edge section7bmay be formed according toFIG.7b.

It is stressed that any of the additional and/or optional features described above in relation to the embodiments inFIGS.5a-5b,6a-6band7a-7balso may be combined with the embodiment according toFIGS.7cand7d.

In any of the embodiments in the present disclosure, there may also be anupper cavity48 between theupper groove wall14cand theupper surface8cin a locked position of the first1 and second1′ panel. Theupper cavity48 may be located in the second edge second7band optionally also in thefirst edge section7a. Thereby, there is more space provided in thesecond edge section7bfor the upwardly bendinglocking element8.

Additionally, it is clear that there may be at least onefirst edge section7aand at least onesecond edge section7b. In particular, there may be a plurality of first7aand second7bedge sections along the edge. The first7aand second7bedge sections may be arranged alternately. In particular, the edge sections may be arranged in a sequence along the edges such as {7a,7b,7a}, {7a,7b,7a,7b,7a} or {7a,7b,7a,7b,7a,7b,7a} with afirst edge section7aat the corners of the edges. Alternatively, there may be asecond edge section7bat the corners of the edges so that a sequence such as {7b,7a,7b}, {7b,7a,7b,7a,7b} or {7b,7a,7b,7a,7b,7a,7b} is provided along the edges.

FIGS.8a-8cshow vertical displacement of thefirst edge section7athat according to the present embodiment constitutes astart section30 and that is active from an initial first step of the folding action. The embodiments inFIGS.8a-8cand9a-9dmay be understood in conjunction withFIG.13a. Theend section32 that is active during the final step of the folding action is preferably also formed with geometry similar or identical to thefirst edge section7a. Thestart30 and end32 sections are arranged at a first and a second corner section, respectively, of the first1 and second1′ panels, adjacent to theirlong edges4a,4b. A part of theinner surface8aof thelocking element8 is formed as afirst locking surface12athat is essentially parallel with a vertical plane VP and a part of the outer groove wall14ais formed as a cooperating second lockingsurface12bthat preferably is essentially parallel with the vertical plane VP. The first and the second locking surfaces12a,12bguide the edges of thepanels1,1′ during the folding action and counteract separation forces that are caused by thesecond edge section7bthat becomes active in a second step of the folding action when the major part of thefirst section7ais in a horizontally locked position with the first12aand the second12blocking surfaces in contact with each other as shown inFIG.8b.FIG.8cshows the adjacent edges in a final locked position.

FIGS.9a-9dshow locking of thesecond edge section7bthat according to the present embodiment constitutes amiddle section31 and that is active from a second step of the folding action when the guiding and lockingsurfaces12a,12bof thefirst edge section7aare active and in contact with each other.FIG.9ashows that a horizontally extending upper protrudingpart25 is formed on the outer and upper part of thelocking element8 and above the upper locking surface11aand is in initial contact with a slidingsurface27 formed on a lower part of theinner groove wall14b. The slidingsurface27 extends essentially vertically upwards to a horizontally extending lower protrudingpart26 formed below thelower locking surface11b. The slidingsurface27 will during the vertical displacement create a pressure force F against the upper protrudingpart25 and this will press the lockingelement8 inwardly towards the upper edge of thefirst panel1 and bend thestrip6 upwards as shown inFIG.9b.

The pressure against the lockingelement8 will create separation forces tending to displace thesecond panel1′ horizontally away from thefirst panel1, but that are counteracted by the first and the second locking surfaces12a,12bof thefirst edge section7a. The pressure that is needed to lock the edges may be reduced if the slidingsurface27 is essentially vertical and extends over a substantial vertical sliding distance SD, measured vertically over a distance where theinner groove wall14bis in contact with theouter surface8bof the locking element during the vertical displacement, and/or if the vertical extension VE of thelocking element8, defined as the vertical distance from the lowest point on the upper surface of thestrip6aand to theupper surface8cof thelocking element8, is large. Preferably, the inclination of the slidingsurface27 is 10-30 degrees in relation to a vertical plane VP and the vertical sliding distance SD is 0.2-0.6 times the size of floor thickness T. A vertical sliding distance SD of 0.3-0.5 times the size of floor thickness T is even more preferred. Preferably, the vertical extension VE of thelocking element8 is 0.1-0.6 times the size of floor thickness T. 0.2*T-0.5*T is even more preferred.

An upward bending of a strip is suitable for wood based cores, such as for example HDF, since the fibres in the upper part of the strip that are sensitive to pulling forces and shear stress will be compressed and the fibres in the lower and stronger part of the strip that are more resistant to pulling forces and shear stress will be stretched. A considerable amount of bending deflection29 may be reached and astrip6 that extends horizontally from the upper edge about 8 mm or with the same distance as the floor thickness T may be bended upwards about 0.05-1.0 mm, e.g. 0.1 mm or 0.5 mm. Here, a bending deflection29 is defined as a vertical distance, in a direction perpendicular to the horizontal plane HP, from a horizontal plane HR being parallel and essentially coinciding with therear side60 of thefirst panel1 in an unlocked state to an outermost and lowermost part of thestrip6. Thus, the bending deflection29 typically varies along the edge of thefirst panel1 and also varies during the various stages of the locking. A maximal bending deflection29 may be located in a middle portion of asecond edge section7balong a length direction of the edges.

FIG.9cshows an embodiment according to which the upper and lower locking surfaces11a,11bwill start to overlap each other already when the upper surfaces ofpanels1,1′ are still spaced vertically. This means that thestrip6 will pull thesecond panel1′ comprising anupper support surface16 towards alower support surface15 formed on the edge of afirst panel1 to a final locked position and this will reduce the pressure force that is required to lock thepanels1,1′. An additional advantage is that the vertical locking may be made with a pretension such that thestrip6 is slightly bended upwards in locked position as shown inFIG.9d. The remaining bending deflection29 in the locked position may be about 0.05-0.30 mm, e.g. 0.1-0.2 mm, when the lower and upper support surfaces15,16 are in contact with each other. According to this embodiment, the locking system is configured such that in the locked position amiddle section31 comprises astrip6 that is upwardly bended compared to its unlocked position and astart section30 that comprises a strip which is essentially in a similar locked position than in an unlocked position. It is understood that there may be transition parts between the first7aand second7bedge sections wherein the strip is upwardly bended. According to a different embodiment, the strip of the start section may even be slightly bended backwards in locked position.

Another advantage is that problems related to thickness tolerances of the panels may be avoided since even in the case that thesecond panel1′ is thicker than thefirst panel1 and normally will hit thesub floor35 before the upper surfaces are in the same horizontal plane, locking may be made with offset upper edges where the surface of the second edge is above the first edge and the strip will pull the panels to a correct position with horizontally aligned upper surfaces and upper and lower support surfaces15,16 in contact with each other. Such locking function is also favorable when the floor panels are installed on a soft underlay, such as foam, and a counter-pressure from the sub floor cannot be used to prevent a downward bending of thestrip6.

A strip formed in soft materials such as an LVT core comprising thermoplastic materials and filler may not snap back towards the initial position after the locking. This may be solved with a joint geometry where theupper groove wall14cis formed to be in contact with theupper surface8cof thelocking element8 during the final stage of the locking action such that the lockingelement8 and thestrip6 are pressed downwards. The locking system may also be formed with an outer andlower support surface15athat cooperates with theprojection46 during locking in order to press thestrip6 downward to or towards its initial position as shown inFIG.9b.

FIG.9eshows that thestrip6 may be formed such that an inner part6cis bended slightly downwards and anouter part6dis bended slightly upwards. Such strip bending and compression will also bend and displace thelocking element8 inwards toward the firstupper edge43. The upper and lower locking surfaces11a,11bmay even in this embodiment overlap each other during locking when the first and the second panels are still vertically displaced in relation to the final locked position with thesecond panel1′ spaced vertically upward from thefirst panel1.

FIGS.10aand10bshow that rotating jumping tool heads18 may be displaced horizontally and may be used to form cavities42, nonlinear grooves36 or may be displaced vertically and may be used to formgrooves37 with different depths in apanel1.FIG.10cshows another cost efficient method to form cavities42 orgrooves36,37 with arotating carving tool40. A tool rotation of therotating carving tool40 is synchronized with a displacement of thepanel1 and eachtooth41 forms one cavity42 at a predetermined position and with a predetermined horizontal extension along an edge of apanel1. It is not necessary to displace thecarving tool40 vertically. Acarving tool40 may have several sets ofteeth41 and each set may be used to form one cavity. The cavities42 may have different cross sections depending on the geometry of the teeth. Thepanel1 may be displaced with or against the tool rotation.

This production technology may be used to form the first7aand the second7bedge sections.

FIGS.11a-11fshow that arotating tool17 may be displaced horizontally along the lockingelement8 or the lockinggroove14 and a first7aand a second7bedge section will be formed when the tool initially removes the upper protrudingpart25 of the locking element and then a part of theinner surface8aof the locking element, or initially removes the lower protrudingpart26 of the lockinggroove14 and then a part of the outer groove wall14aof the lockinggroove14. This method may be used to form the edge sections in a very efficient way. The horizontal displacement of therotation tool17 may be at or less than about 1.0 mm, e.g. 0.5 mm or 0.2 mm.

FIGS.12a-12bshow afixed carving tool22 and a part of the edge of thesecond panel1′ that is shown with thesurface layer2 pointing downwards. Carving may be used to form an essentiallyhorizontal locking surface11bin aninner groove wall14bof the lockinggroove14 even when the lockingsurface11bcomprises a tangent line TL that intersects the outer groove wall14a. A more detailed description of carving may be found in WO 2013/191632.

FIG.13ashows a vertical folding of asecond panel1′ against afirst panel1, comprising a locking system according toFIGS.8a-cand9a-d. The edges comprise astart section30 that is formed as afirst section7a, amiddle section31 that is formed as asecond section7band anend section32 that is formed as afirst section7a. The first12aand second12blocking surfaces are guiding surfaces of the start section that prevent separation and thepanels1,1′ are folded together with upper edges in contact.FIG.13bshows an embodiment of ashort edge4cof thefirst panel1 comprising a middle section being asecond edge section7band having an upper protrudingpart25 with an upper locking surface11aand afirst edge section7aon each side of themiddle section7bcomprising guiding surfaces12a. A part of theinner surface8aof thelocking element8 has been removed at themiddle section7bin order to form a space S that allows an inward turning of thelocking element8, cf.FIG.5b.FIG.13cis a top view of theshort edge4cof thefirst panel1 as shown inFIGS.13aand13band shows that a part of thestrip6 at a transition part6c, located between the first7aand the second7bedge section, is twisted during the vertical folding since the strip is flat in thefirst edge section7aand bended upwards in thesecond section7b. The twisting increases the locking pressure that has to be used to lock the edges. Twisting may be reduced or even eliminated if needed with ahorizontal cavity28 formed in thestrip6 between the first7aand the second7bedge sections as shown inFIG.13d.

FIGS.14a-14eshow different embodiments of the disclosure. The embodiments inFIGS.14a-emay be combined with any of the embodiments of the disclosure.FIG.14ashows floor panels comprising anHDF core5 and astrip6 which is essentially formed in thelower part5bof thecore5 that has a higher density than the middle part. At least parts of the lockinggroove14 and/or thelocking element8 may be coated with afriction reducer22 in order to reduce friction during locking. For example, thefriction reducer22 may comprise wax. Other exemplary friction reducing substances include oils. Parts of the lockinggroove14 and/or thelocking element8 may be impregnated with a reinforcement agent, e.g. resins, in order to reinforce parts adjacent to upper and lower locking surfaces11a,11b. Exemplary reinforcement agents include a thermoplastic, a thermosetting resin or a UV curing glue.

FIG.14bshows a locking system formed in a rathersoft core5. Thestrip6 and thelocking element8 have been made larger. A lower essentiallyhorizontal locking surface11bmay be formed by an inclined rotatingtool17 and with a locking angle LA that may be as low as 20 degrees. It is clear that other locking angles LA are equally conceivable. In non-limiting examples, a locking angle LA between 0° and 45° may be formed by theinclined tool17.

FIG.14cshows that forming of thelower locking surface11bmay be made with a rotating jumping tool that only removes material mainly within thesecond edge section7b. An advantage is that thelower locking surface11bmay be formed with a rotating tool that will not reduce the vertical extension of thesecond locking surface12b.

FIG.14dshows that in some embodiments thefirst section7amay comprise locking means11a,11bthat lock the edges vertically, preferably mainly by material compression. The locking means may be lockingsurfaces11a,11b. In general, theedge sections7a,7bmay comprise complementary locking means as described inFIGS.1a-1e, for example asmall tongue10 and groove9 at the adjacent edges as shown inFIG.1a.

FIG.14eshows thatpanels1,1′ with different thicknesses may be produced with the same tool position in relation to thesurface layer2. This means that thestrip6 will be thicker and more rigid in thicker panels. This may be compensated by removal of materials at thelower part6dof thestrip6 and all panels may comprise astrip6 with similar flexibility and deflection properties.

FIGS.15a-15dshow a second principle of the disclosure. The lockingelement8 comprises an upper locking surface11aformed at theinner surface8aand the lockinggroove14 comprises alower locking surface11bformed in the outer groove wall14a. A strong vertical locking may be accomplished if the locking surfaces11a,11bare essentially horizontal, e.g., within 20 degrees of horizontal. Preferably, a tangent line TL of the upper locking surface11aintersects an adjacent wall of the upper edge. Moreover, a tangent line TL of thelower locking surface11bpreferably intersects an adjacent wall of the lockinggroove14. Locking is accomplished with a downward bending of thestrip6 wherein thelocking element8 is turned outwards as shown inFIG.15b. A problem is that thestrip6 may still be in a backward bended position and the locking surfaces11a,11bmay be spaced vertically when the upper edges of thepanels1,1′ are aligned horizontally as shown inFIG.15c. An upper guiding surface13ais therefore formed as an extension of the upper locking surface11aand a lower guiding surface13bis formed as an extension of thelower locking surface11b. The locking surfaces11a,11band the guiding surfaces13a,13bare configured such that the guiding surfaces13a,13boverlap each other during locking and during the downward bending of thestrip6 when theupper surface2 of thesecond panel1′ is spaced vertically upwards from theupper surface2 of thefirst panel1.

FIGS.16a-16bshow that a locking system according to the second principle may comprise a first7aand asecond edge section7bsuch that the geometry of thelocking element8 and/or the lockinggroove14 varies along the edge. Preferably, thefirst edge section7acomprises only locking means that lock the edges in a horizontal direction and thesecond edge section7b, that according to this embodiment is amiddle section31, comprises horizontal and vertical locking means. According to the present embodiment, astart section30 and anend section32 both arefirst edge sections7a. An advantage of the present embodiment is that the locking may be made with a lower pressure force that only has to be applied when thesecond panel1′ is folded to a rather low locking angle that may be about 5 degrees or lower. The removal of the upper11aand/or lower11blocking surfaces within thefirst edge sections7amay only have a marginal negative influence on the vertical locking strength since the part of the edges that constitutes afirst edge section7ais locked vertically by the adjacentlong edges4a,4bas shown inFIG.16b.FIG.16cshows that the locking system may be configured such that a controlledcrack23 occurs in the material of thecore5, e.g. a material comprising wood fibres. In non-limiting examples, the material may be HDF material or material from a particle board. Moreover, thecrack23 may be provided parallel to a fibre direction of the material. Thecrack23 may extend to a depth of about 1 mm to about 5 mm. Thecrack23 may extend along the entire edge of thefirst panel1 or, alternatively, only along a part thereof, e.g. in a middle part. The advantage is that thestrip6 will be easier to bend downward during locking than upwards in the locked position. According to the embodiment inFIG.16c, lower and upper support surfaces15,16 are formed in an upper part of thepanels1,1′.

FIGS.17a-17dshow that acore material5 may be locally modified such that it becomes more suitable to form a flexible andstrong strip6. Such a modification may be used in all embodiments of the disclosure.FIG.17ashows that aresin20, for example athermosetting resin20 such as, for example, melamine formaldehyde, urea formaldehyde or phenol formaldehyde resin, may be applied in liquid or dry powder form on a balancingpaper3 or directly on acore material5. For example, the balancingpaper3 may be a melamine formaldehyde impregnated balancingpaper3. The resin may also be locally injected into thecore5 with high pressure.FIG.17bshows that acore material5, preferably a wood based panel for example an HDF board or a particle board, may be applied on impregnatedpaper3 with the addedresin20 prior to lamination.FIG.17cshows a floor board after lamination when the surface layers2 and thebalancing layer3 have been laminated to thecore6. Theresins20 have penetrated into thecore5 and cured during lamination under heat and pressure.FIG.17dshows an edge of afirst panel1 comprising astrip6 formed in one piece with thecore5. Thestrip6 is more flexible and comprises a higher resin content than other parts of thecore5. The increased resin content provides a material that is very suitable to form a strongflexible strip6 that during locking may be bent.

FIGS.18a-18fshow that the entire edge of thesecond panel1′ comprising an essentially horizontallower locking surface11bhaving a tangent line TL that intersects a wall of the lockinggroove14 may be formed withrotating tools17 that are angled away from thechain33 and thebelt34 and a carving tool19 that preferably as a last machining step forms the lockingsurface11b.

FIGS.19a-19eshow that the edge of thefirst panel1 may be formed initially with largerotating tools17 that are angled away from thechain33 and thebelt34. The first and thesecond edge sections7a,7bare formed with a jumpingtool18 as shown inFIG.19f. A rotating scraping tool may also be used.

FIGS.20a-20dshow a locking system that is particularly suitable and adapted to be used on the long edges ofpanels1,1′ that are locked with a fold down system according to an embodiment of the disclosure. The locking system comprises an upper10aand alower tongue10bthat cooperate with an upper9aand a lower9btongue groove and that lock the edges vertically at least in a first direction upwards. A lockingstrip6 with alocking element8 cooperates with a lockinggroove14 in an adjacent panel and locks the panel edges horizontally. Alower protrusion38 is formed on an edge of thesecond panel1′ and anupper part6aof thestrip6 locks the edges in a second vertical direction downwards. The locking system is configured such that a high friction is obtained between the long edges and along the edges when they are in an almost locked position and when the first and second locking surfaces12a,12bof thefirst edge section7aof the short edge locking system are in contact with each other and the upper11aand lower11blocking surfaces of thesecond edge section7bare spaced vertically such that no separation forces are active. This is explained more in detail inFIGS.21a-21e. The high friction is mainly obtained with locking surfaces formed on thelocking element8 and the lockinggroove14 that are more inclined with respect to a horizontal plane HP and comprises a higher locking angle LA than the so called “free angle” defined by a tangent line TL to a circle with a radius R equal to the distance from the locking surfaces of the locking element and the locking groove to the upper part of the adjacent edges.FIG.20bshows that the locking system is configured such that in an up angled and locked position there are at least three contact points where the edges are pressed against each other: a first contact point Cp1 between the upper edges, a second contact point Cp1 between the lockingelement8 and the lockinggroove14, and a third contact point Cp3 between thelower tongue10band the lower tongue groove9b. Alternatively, the contact points may be contact surfaces. It is understood that each of the contact points forms a contact line or a contact surface along the edges.FIGS.20cand20dshow that the locking system may be formed with a low material waste in connection with the first cutting step comprising largerotating saw blades17 and carving tools19 when a large laminated board is separated intoindividual panels1,1′.

FIGS.21a-21eshow the position of the long4a,4bandshort edges4c,4dduring the vertical folding.FIG.21ashows asecond panel1′ that is angled with itslong edge4bagainst a long edge4aof previously installedpanel1″ in a previous row and folded with itsshort edge4dagainst ashort edge4cof an installedfirst panel1 in the same row.FIG.21bshows thelong edges4a,4bof the second1′ and the previously installedpanel1″ in a partly locked and up angled position when three contact points Cp1, Cp2, Cp3 are pressed against each other in order to create a friction along the long edges in an up angled position.FIG.21cshows thelong edges4a,4bof the previously installedpanel1″ and thefirst panel1 in a completely locked position.FIG.21dshows that the first and second locking surfaces12a,12bare in contact with each other in thefirst edge section7aandFIG.21eshows that at the same time thelocking element8 and its upper protruding part in thesecond edge section7bis spaced from the lockinggroove14 and its slidingsurface27 such that no separation forces are active. This means that the separation forces created by thesecond edge section7band the bending of thestrip6 are counteracted by the first and second locking surfaces12a,12bof thefirst edge section7aand the friction along thelong edges4a,4bcreated by a pretension and a contact preferably at three contact points Cp1, Cp2, Cp3 along the long edge locking system. As an example, it may be mentioned the locking system may be formed with afirst edge section7athat extends with an edge distance ED of about 2-8 cm, for example 5 cm, from a long edge4aas shown inFIG.21aand with a locking element comprising a vertical extension of about 0.5-6 mm, for example 2, 3 or 4 mm. Thesecond edge section7bmay start at a horizontal distance from a long edge of about 15-35%, e.g. 20%, of the length of the edge. The long edges may be folded to an angle of about 1-7 degrees, for example 3 degrees, before thelocking element8 is in contact with the lockinggroove14 and such a low angle may be used to form a long edge locking system that creates a very high friction along the long edges in a partly locked position where the upper part of thelocking element8 of one long edge overlaps vertically a lower part of the lockinggroove14 of an adjacent long edge. Preferably, the long edge locking system is configured such that a locking angle of 3-5 degrees may be reached before the locking element and the locking groove of thesecond section7bare in contact with each other.

FIGS.22a-22dshow embodiments of locking systems that may be formed with pretension in a partly locked position as described above. The locking systems according toFIGS.22a-22dare particularly suitable and adapted to be used on the long edges ofpanels1,1′. The shown locking systems inFIGS.22a-22dillustrate that the locking systems inFIGS.21band21cmay be formed with a fourth contact point Cp4 located at an upper part of atongue10 and a tongue groove9.

FIG.23a-23dshow that all embodiments of the disclosure may be used to lock for example furniture components where asecond panel1′ comprising a lockinggroove14 is locked vertically and perpendicularly to afirst panel1 comprising astrip6 and with alocking element8. Thestrip6 may initially bend upwards or downwards during the vertical displacement of thesecond panel1′ against thefirst panel1 and thelocking element8 may comprise locking means that lock horizontally parallel to a main plane M1 of the first panel and vertically parallel to the a plane M2 of thesecond panel1′. The main plane M1 of thefirst panel1 may be defined as a horizontal plane that is essentially parallel with alower side80 of thefirst panel1. The main plane M2 of thesecond panel1′ may be defined as a vertical plane that is essentially parallel with anouter side82 of thesecond panel1′. Thepanels1,1′ may have a first7aand a second7bedge section as described above. Thefirst edge section7amay be formed such that the lockingelement8 is in contact with the lockinggroove14 when the lockingelement8 and the lockinggroove14 of thesecond section7bare spaced from each other as shown inFIGS.23aand23c.

FIGS.24a-24eshow that the locking system of a first1 and a second1′ panel may be formed with a first and asecond locking element8,8′ and a first and asecond locking groove14,14′. According to the present embodiment, the first8 and second8′ locking elements and the first14 and second14′ locking grooves extend along the entire edge of thefirst panel1 andsecond panel1′, respectively. Alternatively, however, thesecond locking element8′ and thesecond locking groove14′ may extend along a part of the edge of thefirst panel1 andsecond panel1′, respectively, wherein an extension of thesecond locking element8′ is smaller than or substantially equal to an extension of thesecond locking groove14′. Thesecond locking element8′ and thesecond locking groove14′ may be used to prevent edge separation and to lock the panels horizontally and may replace the first and second locking surfaces12a,12b. Preferably, the lower and inner part(s) of thesecond locking groove14′ and the upper and outer part(s) of thesecond locking element8′ comprise guiding surfaces, for example rounded parts as shown inFIG.24a, that engage with each other and press the upper edges towards each other such that separation forces are counteracted. As an alternative, the one or both overlapping locking surfaces11a,11bmay be removed or the entirefirst locking element8 may be removed at a corner section of first edge, e.g. between 5% and 20% of a total length of the first edge.

A vertical extension of thesecond locking element8′ and/or thesecond locking groove14′ may vary along the first and/or second edge, respectively. The vertical extension may vary from a maximal extension to a minimal extension. The variation may be periodic. At the maximal extension, a top surface of thesecond locking element8′ may engage with an upper groove wall of thesecond locking groove14′. At the minimal extension, there may be a cavity between the top surface of thesecond locking element8′ and the upper groove wall of thesecond locking groove14′.

Avertical flex groove39 may be formed adjacent to and preferably inwardly of the lockinggroove14 in all embodiments of the disclosure.

This embodiment offers the advantages that continuous grooves and locking elements without any edge sections may be used and this will simplify the forming of the locking system. A locking system with high vertical and horizontal locking strength may be formed. The space S between thefirst locking element8 and thefirst locking groove14 allows a turning and/or displacement of thelocking element8 as described in the previous embodiments. The horizontal distance D1 between theinner surfaces8aof thefirst locking element8 and theouter surface8b′ of the second8′ locking element is preferably at least about 30% the floor thickness FT in order to provide sufficient flexibility and locking strength. The horizontal distance D1 may be as small as about 20% of the floor thickness. More generally, D1 may be between 20% and 80% of FT. An upper part of thefirst locking element8 is preferably located closer to the panel surface than an upper part of thesecond locking element8′. Alternatively, however, the upper part of thefirst locking element8 may be located closer to the panel surface than the upper part of thesecond locking element8′. This may reduce separation forces since thesecond locking element8′ will become active before thefirst element8 is in contact with the lockinggroove14.

FIG.24fshows a more compact version wherein the first14 and the second14′ locking grooves are connected to each other. Thesecond locking groove14′ forms an outer part of thefirst locking groove14. The locking system may have one or a plurality of pairs lower and upper support surfaces that are configured to cooperate in a locked state of the panels. For example, support surfaces15,16 may be provided between the inner and lower part of thefirst panel1 and the outer and lower part of thesecond panel1′, and/or support surfaces15′,16′ may be provided between the upper part of thesecond locking element8′ and the upper part of thesecond locking groove14′. A part of thelocking strip6 and thesecond locking element8′ protruding beyond anouter strip portion50, preferably outside thesecond locking element8′, may be removed at a corner section of the first edge in order to eliminate separation forces during the initial stage of the locking when thesecond panel1′ is angled down towards thefirst panel1.

FIGS.25a-25eillustrate various embodiments of one or a plurality offlex grooves39 For simplicity, thesecond locking element8′ and thesecond locking groove14′ are not shown but may be formed in the edge of the first1 andsecond panel1′ in all embodiments ofFIGS.25a-25dand26a-26d.FIG.25ashows afirst panel1 with a plurality of first andsecond edge sections7a,7band aflex groove39 that extends along the entire edge of thesecond panel1′.FIG.25aalso shows that at least a part of theprojection46 may be removed and this may in some embodiments simplify the forming ofsecond edge section7b.

Theflex groove39 may also extend along a part of the edge of thesecond panel1′. In the embodiment inFIG.25btheflex groove39 has two walls in a direction along the edge and is located in a center portion of the edge in the length direction thereof. Preferably the flex groove is formed in a center portion that corresponds to the location of the second edge portion(s)7bwhere the bending of thestrip6 and vertical locking takes place.FIG.25bshows that the first7aand the second7bedge portions may be formed by removal of material in the lockinggroove14 only. An advantage is that only one jumping tool or rotating carving tool is needed at one short edge in order to form the first and second section. In the embodiment inFIG.25ctheflex groove39 is at least partly open towards one edge side and only has one wall in a direction along the edge so that it is located in a peripheral portion of the edge in the length direction thereof.

Generally, it is noted that each wall of the flex groove may be vertical or, alternatively, have a transition region so that a depth of the flex groove increases along the edge from a minimal depth to a maximal depth.

Moreover, there may be two ormore flex grooves39 arranged along the edge. In the embodiment inFIG.25dthere are twoflex grooves39 which are at least partly open towards a respective side edge, each having one wall in a direction along the edge, and located in opposite peripheral portions of the edge in the length direction thereof.

Preferably, theflex groove39 does not extend entirely through thesecond panel1′. By way of example, theflex groove39 may have a vertical extension between 30% and 60% of a maximal thickness of the panel, e.g. 40% or 50%.

As shown in the top views of thefirst panel1 inFIGS.26a-26b, one or a plurality ofslits49 may be formed in thestrip6 along the edge of thefirst panel1 in order to increase the flexibility of the strip while still maintaining sufficient locking strength. A cross-sectional shape of theslit49 may be rectangular, square, circular, oval, triangular, polygon shaped, etc. Preferably, the shapes of theslits49 are the same along the edge, but varying shapes are also conceivable. The slits may be formed in a cost efficient way with a rotating punching tool. Theslits49 may be provided in all embodiments described in the disclosure. Such slits and the previously describedflex grooves39 may be combined in all embodiments of the disclosure. Thefirst panel1 may have aslit49 and the second panel may have aflex groove39. Theslits49 are preferably provided inwardly of thelocking element8. Preferably, theslits49 extend entirely through thestrip6 to therear side60. Alternatively, however, theslits49 may not extend through the strip. The slits may have a vertical extension between 30% and 60% of a minimal thickness of the strip. The slits may be provided in theupper strip surface6a. In the embodiment inFIGS.24a-24dtheslits49 may be provided in astrip surface66 connecting theside wall45 and thesecond locking element8′ or in astrip surface67 connecting thefirst locking element8 and thesecond locking element8′. Alternatively, or additionally, the slits may be provided in therear side60 of thefirst panel1.

In the embodiment inFIG.26b, theslit49 is open towards one edge side and has only one wall in a direction along the edge. Such slit offers the advantage that thesecond section7bmay be used as a start section. Theslit49 will increase the flexibility of the strip and separation forces will be lower during the initial stage of the locking until thefirst edge section7abecomes active. Asimilar slit49 may be formed in the opposite side edge.

Generally, it is noted that each wall of the slits may be vertical, i.e. parallel with a direction perpendicular to the horizontal plane. For example, in the embodiment inFIG.26bwherein theslits49 have a circular shape, the inner surface of theslit49 may be cylindrical. Alternatively, however, the wall may have a transition region so that a depth of the slit increases from a minimal depth to a maximal depth. For example, in the embodiment inFIG.26b, the inner surface of theslit49 may be frustoconical.

FIGS.27a-27cshow an embodiment comprising aflexible locking element8 that may be bended and/or compressed inwardly during locking. Theflexible locking element8 is provided at an outer part of thestrip6 and is configured to engage with the lockinggroove14. An outer, lower part of thelocking element8 engages with a lockingsurface11bof thesecond panel1′ in thesecond edge section7b. Moreover, an outer part of thelocking element8 is free with respect to the lockingsurface11bin thefirst edge section7a. Alternative embodiments of the locking surfaces have been described above in relation to other embodiments of the disclosure wherein reference is made thereto. In particular, the outer part of thelocking element8 may be constant along the first edge and the lockingsurface11bmay be shortened in thefirst edge sections7a, cf. the embodiment inFIG.7a-7b. Optionally, the flexible locking element may also be bended upwards and/or downwards during locking.

Such embodiments may be used in floor panels with flexible core materials, for example a core comprising thermosetting plastic material, but may also be used in other applications. As already noted, the locking system may be formed according to any previous embodiment of the disclosure. A horizontal extension of thelocking element8 may be larger than a horizontal extension of the upper surface of thestrip6a. Outer parts of thelocking element8 may have a smaller vertical extension than inner parts of the locking element for increasing the flexibility of the locking element. The major difference as compared to the embodiments disclosed above is that no space S is needed since the lockingelement8 may be bended upwards and/or compressed inwardly as shown inFIG.27b. The first7a,7a′ and thesecond edge sections7bmay be formed with a simple removal of material located at the outer part of thelocking element8, as shown inFIG.27c, or at the inner part of the locking groove14 (not shown).

Thefirst edge section7a′ inFIG.27cis optional and may be replaced by asecond edge section7b. In other words, thesecond edge section7bmay extend all the way to one side edge of thefirst panel1.

Claims (15)

The invention claimed is:

1. A set of floor panels provided with a mechanical locking system and comprising a first panel and a second panel, the second panel being configured to be locked to the first panel by angling, wherein the mechanical locking system comprises:

a strip extending horizontally from a lower part of a first edge of the first panel and a downwardly open locking groove formed in a second edge of the second panel, the strip comprising an upwardly protruding locking element configured to cooperate with the locking groove for locking the first edge and the second edge in a horizontal direction parallel to a main plane of the floor panels,

an upper tongue and a lower tongue configured to cooperate with an upper tongue groove and a lower tongue groove, respectively, for locking the first edge and the second edge vertically at least in a first direction upwards, and

a lower protrusion provided in the second edge of the second panel configured to contact a contacting surface of an upper part of the strip for locking the first edge and the second edge in a second vertical direction downwards,

wherein the contacting surface is inclined upward toward the locking element or is substantially horizontal,

wherein the locking element includes a locking surface extending from and angled with respect to the contacting surface of the upper part of the strip, the locking surface being located between the contacting surface of the upper part of the strip and an upper part of the locking element, and

wherein the upper tongue is spaced from an upper wall of the upper tongue groove in a locked position of the first edge and second edge.

2. The set of floor panels according toclaim 1, wherein the lower tongue extends horizontally beyond an upper portion of the second edge.

3. The set of floor panels according toclaim 1, wherein the upper tongue is configured to be spaced from an upper wall of the upper tongue groove during locking when the second panel is angled with respect to the first panel, when the upper tongue is provided in the upper tongue groove, and when an uppermost edge of the first edge and an uppermost edge of the second edge cooperate with each other.

4. The set of floor panels according toclaim 1, wherein in a locked position of the first edge and second edge there is a space extending below the lower tongue, from the lower tongue to the lower protrusion.

5. The set of floor panels according toclaim 1, wherein the first and second panels each have a long edge and a short edge shorter than the long edge, and wherein the first and second edges are the long edges of the first and second panels, respectively.

6. The set of floor panels according toclaim 5, wherein the long edges are configured to be folded to an angle of about 1-7 degrees before the locking element is in contact with the locking groove.

7. The set of floor panels according toclaim 5, further comprising a short-edge locking system provided on the short edges of the first and second panels, the short edges of the first and second panels including a first short edge of the first panel and a second short edge of the second panel,

wherein the short-edge locking system comprises a short-edge strip extending horizontally from a lower part of the first short edge and a downwardly open short-edge locking groove formed in the second short edge, the short-edge strip comprising an upwardly protruding locking element configured to cooperate with the short-edge locking groove for locking the first short edge and the second short edge in a horizontal direction parallel to a main plane of the floor panels,

wherein at least one of a cross section of the locking element and a cross section of the locking groove varies along the first and second short edges.

8. The set of floor panels according toclaim 1, wherein the contacting surface is inclined upward toward the locking element.

9. The set of floor panels according toclaim 1, wherein the locking surface of the locking element and a locking surface of the locking groove are inclined with respect to a horizontal plane.

10. The set of floor panels according toclaim 9, wherein said locking surfaces of the locking element and the locking groove comprise a higher locking angle than a free angle defined by a tangent line to a circle with a radius equal to a distance from the locking surfaces of the locking element and the locking groove to an upper part of the adjacent edges.

11. The set of floor panels according toclaim 1, wherein upper edges of the first and second edges further provide locking of the first edge and the second edge in the horizontal direction.

12. A set of floor panels provided with a mechanical locking system and comprising a first panel and a second panel, the second panel being configured to be locked to the first panel by angling, wherein the mechanical locking system comprises:

a strip extending horizontally from a lower part of a first edge of the first panel and a downwardly open locking groove formed in a second edge of the second panel, the strip comprising an upwardly protruding locking element configured to cooperate with the locking groove for locking the first edge and the second edge in a horizontal direction parallel to a main plane of the floor panels,

an upper tongue and a lower tongue configured to cooperate with an upper tongue groove and a lower tongue groove, respectively, for locking the first edge and the second edge vertically at least in a first direction upwards, and

a lower protrusion provided in the second edge of the second panel configured to cooperate with an upper part of the strip for locking the first edge and the second edge in a second vertical direction downwards,

wherein the upper tongue is spaced from an upper wall of the upper tongue groove in a locked position of the first edge and second edge, and

wherein the mechanical locking system is configured such that both in an up-angled position and in a locked position there are at least three contact points such that the first edge and the second edge are pressed against each other, a first contact point being provided between upper edges of the first and second edges, a second contact point being provided between the locking element and the locking groove, and a third contact point being provided between the lower tongue and the lower tongue groove.

13. The set of floor panels according toclaim 12, wherein said contact points are contact surfaces.

14. The set of floor panels according toclaim 12, wherein the three contact points are configured to be pressed against each other in a partly locked position and in the up-angled position in order to create a friction along the first edge and the second edge in the up-angled position.

15. A set of floor panels provided with a mechanical locking system and comprising a first panel and a second panel, the second panel being configured to be locked to the first panel by angling, wherein the mechanical locking system comprises:

a strip extending horizontally from a lower part of a first edge of the first panel and a downwardly open locking groove formed in a second edge of the second panel, the strip comprising an upwardly protruding locking element configured to cooperate with the locking groove for locking the first edge and the second edge in a horizontal direction parallel to a main plane of the floor panels,

an upper tongue and a lower tongue configured to cooperate with an upper tongue groove and a lower tongue groove, respectively, for locking the first edge and the second edge vertically at least in a first direction upwards, and

a lower protrusion provided in the second edge of the second panel configured to cooperate with an upper part of the strip for locking the first edge and the second edge in a second vertical direction downwards,

wherein the upper tongue is spaced from an upper wall of the upper tongue groove in a locked position of the first edge and second edge,

the first and second panels each have a long edge and a short edge shorter than the long edge, and wherein the first and second edges are the long edges of the first and second panels, respectively,

wherein the mechanical locking system further comprises a short-edge locking system provided on the short edges of the first and second panels, the short edges of the first and second panels including a first short edge of the first panel and a second short edge of the second panel,

wherein the short-edge locking system comprises a short-edge strip extending horizontally from a lower part of the first short edge and a downwardly open short-edge locking groove formed in the second short edge, the short-edge strip comprising an upwardly protruding locking element configured to cooperate with the short-edge locking groove for locking the first short edge and the second short edge in a horizontal direction parallel to a main plane of the floor panels,

wherein at least one of a cross section of the locking element and a cross section of the locking groove varies along the first and second short edges, and

wherein said mechanical locking system is configured such that a friction is obtained between and along the long edges when the long edges are in an almost locked position, when first and second locking surfaces of a first edge section of the short-edge locking system are in contact with each other, and when upper and lower locking surfaces of a second edge section of the short-edge locking system are spaced vertically, such that no separation forces are active.

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